1. Field of the Invention
The present invention relates to a three dimensional composite circuit board, and more particularly, to a box shaped composite circuit board which is manufactured by assembling circuit boards or circuit modules having electronic elements therein, thereby miniaturizing the size of an appliance which contains the circuit board.
2. Description of the Prior Art
Generally, a circuit board used in an electric, an electronic or a telecommunication appliance is made of plastic and has a molding surface thereon. The circuit board is provided thereon with a circuit pattern such as a constant-voltage regulating circuit, an amplifying circuit, an oscillation circuit or a synchronizing circuit. The upper surface of the circuit pattern is coated with a non-electrolysis plating. In addition, various electronic elements such as a transistor, a diode, an IC, and an LSI are systematically mounted in the circuit board in accordance with the circuit pattern.
The circuit boards are piled up in a plurality of layers when they are installed in the appliances. A separate device for installing the circuit board into the appliance is required.
However, such a circuit board is generally manufactured to have a two dimensional shape. Accordingly, when a complex circuit pattern is printed in the circuit board, the circuit board requires a large size, so it is difficult to miniaturize the appliance.
In addition, a substantial amount of labor is required to install the circuit board into the appliance. Also, since the circuit boards installed in the appliance should be interconnected with each other, all circuit boards are replaced even when only one of them is faulty, thus causing the repair and replacement cost to be high.
In order to solve the above problems, many improved circuit boards have been proposed. For example, Japanese Patent Laid-open No. 04-208587 discloses a three dimensional circuit module. According to the three dimensional circuit module, a flexible board having electronic elements therein is manufactured as a polyhedral shape, and has a multi-layered structure. A molding material is coated on one side of the flexible circuit board.
However, it is difficult to manufacture the flexible circuit board having the multi-layered structure. In addition, a large space in the appliance is required in order to install the multi-layered flexible circuit boards, so it is difficult to miniaturize the appliance. Furthermore, since the flexible circuit board has a cubic shape, it is impossible to re-use the circuit board which forms the other sides even when a circuit board forming only one side of the cubic is faulty.
In addition, not only is a fixing device for fixing the flexible circuit boards to the appliance required, but also an electromagnetic wave generated from the electronic elements in the flexible circuit board is not shielded, so that the electromagnetic waves may cause the appliance to malfunction and may harm the user.